The invention relates to electronically controlled fuel injection devices for internal combustion engine, comprising a plurality of electrically controlled injectors.
The invention is particularly suitable for use in "multipoint" fuel injection devices, wherein each combustion chamber of the engine is provided with an injector which opens into the induction passage in the immediate vicinity of the respective inlet valve.
The invention more particularly relates to fuel injection devices of the type comprising a plurality of electrically controlled injectors, an electronic unit controlling the injectors responsive to operating parameters of the engine, and a throttle valve assembly having an operator controlled valve in an air induction passage feeding the combustion chambers, each injector having an injector body formed with means for securing it in a recess which opens into the induction passage and a nose formed with at least one fuel outlet passage, defining a mixture chamber connected to an atomization air inlet.
Injection devices are already known (European No. 0,357,498) having an injector which has a chamber provided with an air inlet. As a rule, the air flow to the injectors is drawn from the air inlet of the fuel injection device. Air admission improves atomization of the fuel delivered by the injector.
In a modification (European No. 0,409,170) the flow of additional air drawn from a location upstream of the throttle valve and delivered to each injector is controlled by a three way idling valve which also operates as a regulator for idling operation.
Last, Japanese No. 57,157,058 discloses a fuel delivery device having a sub-section pipe which is branched for delivering air necessary for atomization of fuel in each of the injectors, namely injectors for normal operation and one auxiliary injector for cold start. The branch toward the cold start injector is only open when that injector is used.
Some fuel injection devices have a throttle valve apt to close the induction passage almost completely. The flow of additional air in a line having an inlet located upwardly of the butterfly valve is adjustable by an electrically controlled valve. That air valve is controlled by the electronic unit, responsive to operation parameters of the engine, such as the degree of opening of the throttle valve and the speed of the engine for regulation of the idling speed, the water temperature and the running speed of the engine for cold start. The electronic unit renders cold start of the engine easier; it regulates the idling speed and improves transition when the engine acts as a brake.